United, who lost the title to rivals Manchester City on goal difference last season, opened up the huge advantage by defeating Reading hours after nearest challengers City had lost at Everton.

But the Old Trafford boss said he had expected a far more nail-biting season than one that has left them needing 13 more points - and possibly less - to make sure of another title.

"With Manchester City coming on the scene in the last couple of years, and Chelsea and Arsenal and Tottenham, you have teams vying for that top-four position,'' Ferguson told the Sirius XM radio station.

"I expected it to be really tight. The first point was that, after last season, we wanted to make sure we didn't lose it on goal difference, and that has improved markedly.

"But I never thought we would be 15 points clear at this stage of the season."

Ferguson remains hopeful his charges can eclipse the mark of 95 competition points picked up by Chelsea in 2004-05, targeting 22 points from United's final nine games.

"If we get to 96 points I'd be absolutely delighted. That would be a fantastic season. If we get to that position, we have probably won the league," he said.

United face struggling Sunderland away on Saturday before taking on Chelsea in an FA Cup quarter-final replay at Stamford Bridge on Monday, and Ferguson said he was hoping his players would make it through Tuesday's international fixtures unscathed.

"They played last Friday and they are playing tonight," he said. "Once I know later this evening how many minutes each player has played, I will start to think about my team for Saturday.

"It is a big ask for our squad and something we need to concentrate on, because I need to make sure I pick the right teams."

Ferguson also told the radio station of his regret at having missed out on signing Paul Gascoigne when he moved from Newcastle to Tottenham in 1988.

Gascoigne, who has battled alcoholism in recent years, has recently returned from treatment in the US and said he was feeling optimistic about the future.

And the United boss hailed the former England midfielder's dazzling ability, saying: "He was a fantastic footballer. He was the best player England produced since the days of Bobby Charlton.

"I have always said that, when Paul Gascoigne chose to go to Tottenham ahead of Manchester United, it was a big mistake. He always regretted that."